National Football League TV ratings are up for the first time since 2015, an improvement NFL and television executives attribute to new stars, a fading national-anthem controversy and a much-needed distraction from the political divisiveness shaking the country.

Five weeks into the season, the average TV audience for a game is 15.6 million, up 3% compared with the same period a year ago, according to Nielsen. Ratings remain 16% lower than in the first five weeks of the 2015 season.

The top 15 shows for all of September were NFL games, Nielsen data show, a sign that despite ratings erosion in past seasons, football still is the most popular programming on television.

In prime time, the strength of NFL programming remained evident. Fox and NBC, which carry Thursday night and Sunday night games, respectively, were the only networks to post an uptick in prime-time viewers this broadcast-TV season, which started Sept. 24. The viewership of ESPN’s “Monday Night Football,” however, fell 3%, hurt by several blowout games and competition from postseason baseball.

Troy Vincent, the NFL’s executive vice president of football operations, said ratings were boosted by the quality of play, a crop of young stars and a dearth of off-field distractions, such as players protesting during the national anthem.

“These were conversations that were polarizing around the sport. Now we’re talking around the sport,” said Mr. Vincent.

In Week 5, all four rookie quarterbacks who were picked in the top 10 of last spring’s NFL draft started and won their games. Patrick Mahomes, the 23-year-old quarterback for the Kansas City Chiefs, leads the league in touchdown passes. Jared Goff, also 23 years old, has led the Los Angeles Rams to an undefeated start.

“This is shaping up as the year of the QB,” said Mike Mulvihill, executive vice president, research, for
21st Century Fox’s
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Fox Sports.

A prime example of this came in “Thursday Night Football” on the NFL Network in week three, when two of the worst teams in the league from a year ago—the New York Jets and Cleveland Browns—combined to produce a thriller. In that game, Browns rookie quarterback Baker Mayfield, who was the top pick in the draft, took over midway through the game to lead his team past the Jets, led by quarterback Sam Darnold, the No. 3 pick.

This year’s games also have been historically high-scoring and close, providing a boost. Teams are averaging 24 points a game, the most in NFL history, while the average margin of victory of about 10 points is smaller than any since 1932. Eight games have already gone to overtime, tying the most at this stage since overtime was instituted in 1974.

CBS Corp.’s
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CBS, whose average Sunday afternoon viewership rose to 15.9 million from 14.9 million a year ago, has broadcast rights to the American Football Conference, which includes the undefeated Chiefs and the revitalized Browns.

CBS Sports Chairman Sean McManus said new stars and close games aren’t solely responsible for boosting numbers.

“I do think there is so much unpleasantness out there today and so much divisiveness between different groups that the refuge of NFL football is probably more appealing now than it’s been in a long time,” Mr. McManus said.

From the Archives

San Francisco 49ers quarterback Colin Kaepernick said he will continue to sit during the national anthem as a form of personal protest against the state of race relations in the U.S. He is the most recent in a long string of athletes publicly protesting racial injustice. Photo: AP (Originally Published August 29, 2016)

A growing number of viewers over 50 years old are watching the NFL this season, according to Nielsen. People over 50 view player protests during the national anthem—which have become more muted this season—more negatively than the general population, according to a WSJ/NBC News poll from August. Fox and Wall Street Journal parent News Corp share common ownership.

This year’s uptick in television ratings comes as the NFL is available on an ever-growing number of platforms. An NFL spokesman said that through four weeks of the season, digital consumption is up 65% with an average audience of 326,000 per game. The first two Thursday-night games available on Amazon, NFL digital, Fox digital and Yahoo Sports were up 57% with an average audience of 800,000.

“Sunday Night Football” on
Comcast Corp.’s
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NBC is averaging 19.6 million viewers through five weeks, up a hair from last season’s 19.5 million at this point in the season. That figure also includes the network’s opening NFL game on Thursday, Sept. 6 between the Atlanta Falcons and Philadelphia Eagles, which was delayed for nearly an hour because of lightning. The audience was down 13% from the 2017 Thursday season opener.

“It’s slightly better than we anticipated,” said NBC Sports Chairman Mark Lazarus, who thought heading into the season that ratings would be down “a tick or two.”

Fox’s Mr. Mulvihill said he thinks Fox’s Sunday afternoon ratings, despite being down 2%, have a “real good chance” to be on the plus side by November. “Thursday Night Football” on Fox is keeping pace with the average for the same time a year ago.

“Monday Night Football” ratings on
Walt Disney Co.’s
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ESPN, while down 3% this season, remain higher than they were at the end of last season. ESPN Executive Vice President Burke Magnus said the channel’s upcoming schedule was strong, citing games featuring the Dallas Cowboys, New England Patriots, Green Bay Packers and a potential Super Bowl preview featuring the Rams versus the Chiefs. “Based on what we have remaining, we feel very good,” he said.